SHOCK MONITORING MODERN TECHNIQUES 2

9.1.3 Transcutaneous O2 monitoring

This noninvasive technique for measuring skin PO2 is dependent on
cardiac output and skin perfusion in a stable patient but not in
patients in shock

Gastric Tonometry
Gut perfusion, can be indirectly assessed, using tonometric techniques, to measure the gastric intramucosal pH (pHi).
- Involves instilling saline into a semi permeable balloon, at the end of a modified nasogastric tube, after a period of equilibration, remove the saline and measure the carbon dioxide tension (Pco2), of the saline sample.
-Mucosal ischemia, leads to the production of increased CO2 within the stomach lumen, which is detected as an increased Pco2, in the saline sample.
-Gastric mucosal Pco2 is used with measured arterial bicarbonate to calculate the pHi. -Trauma patients with pHi less than 7.32 have a higher rate of MOF and death.
-Recent technical innovations, have lead to the development, of a semicontinuous gas tonometer, and a model of this device is now available for clinical use.
Gut perfusion using this technique is detected by an elevated mucosal-arterial CO2 gap.
Gas tonometry is automated, and less prone to sampling error.

9.1.4 Serum Lactate

The more important information comes from demonstrating rising or
falling serum lactate levels in response to treatment of shock.
The lactate/pyruvate ratio is also of help in this regard.

Recent developments have led to the availability of bedside testing of serum lactate levels, and an effective clinical method of determining perfusion status through serial measurement of lactate at the bedside in critically ill patients.

In summary it is observed that in shock resulting from
decreased blood volume (oligaemia) there would be on INVESTIGATION:
i)A decreased cardiac output
ii)An increased peripheral resistance and
iii)Decreased central venous pressure


Metabolic effects of untreated shock include:
* A decreased, oxygen consumption
* Hyperglycaemia followed by hypoglycaemia in late stages
where glycogen stores have been depleted
* A rise in blood lactate and pyruvate
* Metabolic acidosis
* Increase in ACTH secretion
* Decreased urine output (<0.5 ml.kg body wt.)
Modern techniques can help give you information, if you look for it
Any questions be sent to drmmkapur@gmail.com
All earlier posts are stored in archives for access and review